1. Field of the Invention
The present invention relates to a fire alarm system transmitter for use in a fire alarm system.
2. Description of the Related Art
In a transmitter for use in a fire alarm system, a printed circuit board on which a terminal block is fixed is housed inside the transmitter. In an operation of mounting the transmitter to a mounting box, an electric wire extended to an inside of the mounting box is connected to the terminal block, and then, the transmitter is arranged in the mounting box. Finally, a front opening of the mounting box is covered with a plate serving as a decorated frame. Thus, the operation is completed.
Here, in the printed circuit board, in order that a circuit component is not limited in terms of mounting and a mounting area is maximized, the terminal block is disposed along one side of the printed circuit board. At this time, in consideration of an insulating property for the purpose of preventing contact between the circuit component and the electric wire, an insertion hole is formed in a side wall at one side of a casing, and the electric wire is pulled out through the insertion hole (see JP 2002-170168 A, for example).
However, a creepage distance (clearance) from the terminal block to the insertion hole as an outside of the casing is set to be short, and hence the insulating property may be adversely affected. At this time, in order to separate the entire side wall on the terminal block side of the casing from the terminal block, it is necessary to increase an entire size of the casing. As a result, there arises a problem in that a resin (material) amount of the casing is increased and an operation of arrangement into the mounting box is difficult.